Field of the Invention
The present invention relates to a flux used for a resin flux cored solder, a flux used for a flux coated solder having its surface coated with a flux, a resin flux cored solder using a flux, and a flux coated solder.
Description of Related Art
A resin flux cored solder is a material wherein a wire solder is filled with a solid flux. A flux coated solder is a material wherein a wire solder is coated with a flux. A flux used for a soldering eliminates chemically a metallic oxide from a metallic surface of an object to be soldered at a soldering process in order to make metallic elements possible to move at a boundary therebetween. By employing the flux, it forms a metallic compound between the solder and the metallic surface of the object to be soldered for establishing a strong joint.
The flux requires characteristics, such as elimination of the metallic oxide, prevention of a reoxidation at a solder fusion, a lower surface tension of the solder, etc. When using such a flux for the resin flux cored solder or the flux coated solder, the flux comprises an activator for improving a wettability of the metallic surface by eliminating an oxidized film therefrom and a base material, such as rosin, etc. for protecting the activator from heat. Japanese Patent Application Publication No. 2008-100279 discloses that a rosin resin, such as a rosin ester, etc. is used as a base resin (corresponding to a base material of the present invention that will be described hereinafter) and it is added to the flux for the resin flux cored solder where its amount is within a range of 3-60% by weight, preferably 5-50% by weight.
In general, the flux contains components that volatilizes as a result of heat at the soldering operation. The volatilized components gather to form air bubbles. When the air bubbles blow out, the flux and the solder may fly apart. Japanese Patent Application Publication No. 2012-016737 discloses a flux composition that inhibits the gas from releasing intensively from the flux by generating a lot of extremely fine air bubbles in the flux for the micro degassing.
A part of the components volatilized by the heat during the soldering changes a visible white smoke. If the generated white smoke fills the factory and the like having an especially insufficient exhaust equipment, problems occur wherein it is hard to work for workers and their work efficiency may be reduced.
The flux disclosed in Japanese Patent Application Publication No. 2008-100279 does not take measure to resolve the above described problems. The flux composition disclosed in Japanese Patent Application Publication No. 2012-016737 does not focus on reducing an amount of the generated gas.